Defensive publication

ABSTRACT

A CURABLE FLUOROELASTOMER COMPOSITION HAVING IMPROVED RESISTANCE TO SHRINKAGE DURING MOLDING, WHICH CURES TO A COMPOSITION HAVING OTHER DESIRABLE PROPERTIES SUCH AS GOOD TEAR STRENGTH AND ELONGATION CAN BE MADE BY MIXING THE FOLLOWING: (A) AN ELASTOMERIC COPOLYMER OF VINYLIDENE FLUORIDE AND AT LEAST ONE OTHER FLUORINATED MONOMER, (B) A POLYHDROXYLIC AROMATIC COMPOUND CROSS-LINKING AGENT FOR SAID COPOLYMER, (C) A SUITABLE VULCANIZATION ACCELERATOR, SUCH AS A QUATERNARY PHOSPHONIUM OR AMMONIUM COMPOUND, (D) A SUITABLE METAL COMPOUND SUCH AS A DIVALENT METAL OXIDE OR HYDROXIDE, AND (E) A POLYEPOXIDE HAVING A FUNCTIONALITY OF AT LEAST TWO. PARTICULARLY USEFU COMPOSITIONS OF THIS TYPE CAN BE MADE FROM COPOLYMERS OF VINYLIDENE FLUORIDE AND HEXAFLUOROPROPYLENE (POLYMERIZED IN A MOLAR RATIO OF 85:15 TO 50:50) AND, PER 100 PARTS OF COPOLYMER, 0.1-5 PARTS OF HEXAFLUOROISOPROPYLIDENE-BIS(4 - HYDROXYBENZENE), 0.1-3 PARTS OF BENZYLTRIPHENYLPHOSPHONIUM CHLORIDE, 1-20 PARTS OF MAGNESIUM OXIDE OR A MIXTURE OF MAGNESIUM AND CALCIUM OXIDES, AND 0.5-10 PARTS OF DIFUNCTIONAL EPOXY RESIN MADE FROM EPICHLOROHYDRIN AND BISPHENOL. A. CURING IS ACCOMPLISHED BY HEATING FOR 3-30 MINUTES ABOUT 149204*C. AND OPTIONALLY POSTCURING FOR 1-48 HOURS AT ABOUT 204-260*C.

DEFENSIVE PUBLICATION UNITED STATES PATENT OFFICE Published at the request of the applicant or owner in accordance with the Notice ct Dec. 16. 1969, 869 0.G. 687. The abstracts of Defensive Publication applications are identified by distinctly numbered series and are arranged chronologically. The heading of each abstract indicates the number of pages of specification, including claims and sheets or drawings contained in the application as originally filed. The files or these applications are available to the public for inspection and reproduction may be purchased for 30 cents a sheet.

Defensive Publication applications have not been examined as to the merits of alleged invention. The Patent Ofiice makes no assertion as to the novelty ot the disclosed subject matter.

PUBLISHED OCTOBER 30, 1973 T915,011 FLUOROELASTOMER COMPOSITION James Ray Hoover, Wilmington, and James Daniel MacLachlan, Hockessin, Del., assignors to E. I. du

Pont de Nemours and Company, Wilmington, Del.

Filed June 30, 1972, Ser. No. 268,023 Int. Cl. C08g 45/04 U.S. Cl. 260-836 No Drawing. 16 Pages Specification A curable fiuoroelastomer composition having improved resistance to shrinkage during molding, which cures to a composition having other desirable properties such as good tear strength and elongation can be made by mixing the following: (A) an elastomeric copolymer of vinylidene fluoride and at least one other fiuorinated monomer, (B) a polyhydroxylic aromatic compound cross-linking agent for said copolymer, (C) a suitable vulcanization accelerator, such as a quaternary phosphonium or ammonium compound, (D) a suitable metal compound such as a divalent metal oxide or hydroxide, and (E) a polyepoxide having a functionality of at least two. Particularly useful compositions of this type can be made from copolymers of vinylidene fluoride and hexafluoropropylene (polymerized in a molar ratio of 85:15 to 50:50) and, per 100 parts of copolymer, 0.1-5 parts of hexafluoroisopropylidene-bis(4 hydroxybenzene), 0.1-3 parts of benzyltriphenylphosphonium chloride, 1-20 parts of magnesium oxide or a mixture of magnesium and calcium oxides, and 0.5-10 parts of difunctional epoxy resin made from epichlorohydrin and bisphenol A. Curing is accomplished by heating for 3-30 minutes at about 149- 204" C. and optionally postcuring for 1-48 hours at about 204-260 C. 

